My wife Ariella was nice enough to buy me the Rogatchover haggadah this week and I just by chance discovered the Rogatchover in the previous post that related to the two previous posts I had done. A few thoughts on that haggadah: There are so many haggados and new ones keep coming out because all it takes to produce one is the ability to complie from a classic text or texts. However, the Rogatchover haggadah is more than a compilation. The editor actually rewrites each issue the Rogatchover discusses, explaining in clear modern Hebrew what the focal point of the chakira is, citing and explaining the relevant Rambam or gemara, and adding some footnotes to other sources that reference the Rogatchover's chiddush. If you are unfamilar with the Rogatchover, this is a good place to start. The editor sometimes throws in multiple versions of the same chiddush, so the haggadah is somewhat repetitive (Rabbi Kasher in Mefa'aneyach Tzefunos points out that there is a development and refinement of certain ideas in the Rogatchover's writings so a chiddush quoted in a later work may vary slightly from the way it is expressed in an earlier work; the haggadah does not delve into these type of nuances.) I can't tell whether without prior exposure to a work like Mefa'aneyach Tzefunos one's appreciation of the haggadah would be lessened -- my sense is that anyone with a love of lomdus would enjoy it and it would entice the reader's to perhaps approach more of the Rogatchover's works at least through R' Kasher's seforim.
On a different note, why is there no R' Yosef Engel haggadah with a compilation of his chiddushim? This is my son's favorite acharon! Whoever is putting out the Tiferes Yosef on chumash (of which only 2 vol have appeared so far) needs to get cracking on this : )